Daylight Saving Time Could Become Permanent: What Congress Just Approved

Airlines are warning that locking the clocks on daylight saving time could take up to two years to implement, after the House sent the plan to the Senate on a 308-117 vote.

The House voted 308-117 on Tuesday to make daylight saving time permanent nationwide, advancing a bill that has drawn warnings from the U.S. airline industry to the Senate.

The bill, H.R. 139, the Sunshine Protection Act of 2025, would eliminate the twice-yearly clock change and lock the nation’s clocks on daylight saving time. It’s the farthest daylight saving time legislation has advanced in Congress in years, and it now moves to the Senate, where it awaits action in the Commerce, Science and Transportation Committee before it could reach the president’s desk.

Airlines for America, the trade association representing major U.S. passenger and cargo carriers, warned the same day the House passed the bill that the change would have “considerable implications for aviation,” including “passenger disruption, crew and aircraft positioning, and domestic and international connectivity issues.” The group said any switch would need enough lead time to reprogram scheduling systems that airlines build years in advance.

Rep. Vern Buchanan, R-Fla., the bill’s sponsor, said the vote marked a step toward ending a decades-old ritual. “Today, the House took an important step toward ending the outdated practice of changing our clocks twice a year by passing my bipartisan Sunshine Protection Act,” Buchanan said. A companion bill, S. 29, was introduced in the Senate by Sen. Rick Scott, R-Fla.

The House vote broke down largely along a bipartisan line, with Republicans supporting the measure 193-22 and Democrats splitting 114-95 in favor. One independent also voted yes. The bill would repeal the section of the 1966 Uniform Time Act that governs the return to standard time each fall, and it would allow some states to opt out of year-round daylight saving time under specified circumstances.

Not every lawmaker backed the bill. Rep. Mary Gay Scanlon, D-Pa., who offered an unsuccessful amendment in the House Rules Committee to instead make standard time permanent, said locking the clocks on daylight saving time would leave students and workers walking to school or the office in the dark each winter. “Millions of Americans will wake up during the winter months in complete darkness with the sun not rising until long after people get up and travel to school or work or have to go about their days,” Scanlon said on the House floor. Her amendment, the “Sunshine for Our Kids Act,” was defeated in committee, 4-6, a day before the full House approved H.R. 139 under a closed rule, 6-4.

Industry Says Timeline Is Critical

Airlines for America told CBS News that any change should “allow for a significant amount of time to adjust airline schedules, websites, reservation systems, crew scheduling, payroll and the implementation of IT fixes both at the air carriers and any impacted vendors prior to implementation of DST changes.” CBS reported the aviation industry says the shift could take up to 24 months to fully carry out.

Henry Harteveldt, founder of Atmosphere Research Group, told CBS News the technical lift is real but pushed back on the two-year estimate. “There are a lot of different software systems that may need to be reprogrammed within an airline, including reservation, crew scheduling and maintenance, which will have to be adjusted,” Harteveldt said. He put the more realistic timeline at six months to a year, saying of the industry’s two-year figure: “I don’t think it’s going to be a two-year time frame. That seems extreme.”

The measure’s path through the House was not smooth. It advanced through the Energy and Commerce Committee earlier this year as part of the Motor Vehicle Modernization Act, passing 48-1, before the Rules Committee sent it to the floor. Committee Chairman Brett Guthrie, R-Ky., pointed to “the evidence that year-round daylight saving time boosts economic activity and improves public safety.” Rep. Gus Bilirakis, R-Fla., who chairs the Energy and Commerce Subcommittee on Commerce, Manufacturing, and Trade, said permanent daylight saving time would provide “greater consistency, more usable daylight in the evening, and the certainty that comes with ending the twice-yearly clock changes.”

Senate Path Uncertain

No Senate floor vote has been scheduled as of Friday. Senate Majority Leader John Thune, R-S.D., was reported by NBC News as expressing hesitance about locking the clocks by federal mandate. “I just don’t think we want a mandate, and that was tried once before and repealed, but we’re looking at it,” Thune said, according to NBC News. Sen. Tom Cotton, R-Ark., has objected to fast-tracking the Senate companion bill by unanimous consent, NBC News and CNN reported, citing an aide who said the senator retains concerns about the measure.

The U.S. Department of Transportation, which oversees the nation’s compliance with the Uniform Time Act but does not have authority to repeal or change daylight saving time, had not issued a statement specifically addressing the House vote as of Friday. Delta Air Lines, United Airlines, American Airlines and Southwest Airlines have not issued individual statements on the bill; their position has been represented collectively through Airlines for America.

Not everyone in the medical community backs the permanent daylight saving time approach. Sleep-medicine researchers and a coalition of organizations, including the American Academy of Sleep Medicine, the National Sleep Foundation, Save Standard Time, the Sleep Research Society and the Society for Research on Biological Rhythms, have instead pushed for permanent standard time, citing circadian-rhythm and public-health concerns. Dr. Karin Johnson, a physician and professor of neurology at UMass Chan School of Medicine Baystate, testified on the issue on behalf of the American Academy of Sleep Medicine at an April 2025 Senate Commerce Committee hearing.

A Cautionary Precedent Abroad

Airlines elsewhere have dealt with abrupt time-change decisions before. In March 2023, Lebanon’s caretaker government delayed that year’s daylight saving time transition before reversing course days later after what CBS News described as “all sorts of problems.” Middle East Airlines, the largest carrier at Beirut’s Rafic Hariri International Airport, adjusted its flight schedules for about a month, moving departures forward by an hour, after the government’s about-face. The airport briefly operated on two different local times amid the confusion, according to aviation trade outlet AeroTime, which advised passengers to double-check their departure times.

The current biannual clock-change system dates to the 1966 Uniform Time Act. A previous federal attempt at year-round daylight saving time was enacted temporarily during the 1973-74 energy crisis and repealed after public backlash over dark winter mornings — the history Thune appeared to reference in his remarks on the current bill.